21.2 Carotid Endarterectomy

Question 1

A 56-year-old man is listed for carotid endarterectomy 10 days after suffering a cerebrovascular accident.

a) What are the advantages (4 marks)
and disadvantages (4 marks)
of performing the procedure under regional anaesthesia?

Answer 1

Advantages

1 An awake patient provides their
own real neurological monitoring.

2 Monitoring in the early postoperative period
improved as not recovering from general
anaesthetic.

3 Lower need for shunt with its attendant risks;
particulate or bubble embolisation, arterial wall
dissection, kinking, thrombosis.

4 Artery is closed at normal patient blood
pressure; may reduce postoperative
haematoma.
Possibly more stable blood
pressure throughout.

5 Avoids airway instrumentation, general
anaesthetic, and its associated risks
(everything from sore throat to failed
intubation and, more specifically in this
situation, the cardiovascular instability caused
by induction and intubation).

Question 2

b) What local or regional anaesthetic techniques may be used? (3 marks)

Answer 2

Just a list required –
there are only 3 points for this answer.

> > Local anaesthetic infiltration.

> > Superficial cervical plexus block.

> > Deep cervical plexus block.
Combined superficial and
deep cervical plexus blocks.

> > Cervical epidural, although
this is now never used due to its burden of
adverse effects: high block, hypotension.

Question 3

c) How can his risk of perioperative cerebrovascular accident be minimised? (6 marks)

Answer 3

Embolic (biggest risk):
» Avoid shunt use where possible,
or meticulous surgical technique to
avoid thromboembolism or
air embolism when using shunt.

> > Meticulous surgical technique
to avoid dislodgement of atheroma.

> > Perioperative administration of antiplatelets,
usually dual antiplatelet therapy (DAPT).

> > Heparin before cross-clamping.

Ischaemic:
» Use of a shunt if collateral circulation
is inadequate during cross-clamp.

> > Pharmacological management of perioperative hypotension.

Haemorrhagic:
» Pharmacological management of perioperative hypertension.

Question 4

d) Following this procedure, what other specific postoperative complications may occur? (3 marks)

Answer 4

1. > > Postoperative haematoma,
   which may ultimately compromise airway.
2. > > Haemodynamic instability secondary
   to impaired carotid baroreceptor
   reflexes resulting in periods of
   hyper- or hypotension, which may
   precipitate cardiovascular events.
3. > > Cerebral hyperperfusion syndrome,
   occurs from immediately postoperatively
   until a month later.

Chronic hypoperfusion results in
areas of impaired autoregulation.

Increased microvascular permeability
occurs on reperfusion of
previously underperfused areas of brain,
increasing vulnerability to oedema: ischaemia-reperfusion injury.

Extreme hypertension resulting from impaired carotid baroreceptor function postoperatively,

in combination with the previous changes,
may result in oedema and haemorrhage.

Result: hypertensive encephalopathy,
severe headache,
variable neurological deficits,
seizures, cerebral oedema,
cerebral haemorrhage

Question 5

CEA

When

Evidence

Answer 5

Carotid endarterectomy improves outcomes

(reduces risk of fatal or disabling stroke)

of symptomatic patients,

with greater than 50% carotid stenosis
compared with the best medical management

(reduction in arterial pressure,
antiplatelet drugs,
statins or diet to reduce serum cholesterol,
stopping smoking,
controlling diabetes and
reducing alcohol intake).

Neurologically stable patients who
have had a transient ischaemic attack
or stroke should ideally have
carotid endarterectomy within two weeks

if stenosis is 50%–99%. ECST-2
(European Carotid Surgery Trial)

should help determine which of
medical or surgical management
of asymptomatic patients is the better option,
and ACST-2

(Asymptomatic Carotid Surgery
Trial)
aims to determine whether stent or carotid endarterectomy is best for asymptomatic patients.

Once again, the question wants proof of your
understanding about the advantages and disadvantages of the various
possible anaesthetic techniques.

Question 6

CEA surgical approach

Answer 6

A very brief description of the surgical
approach to carotid endarterectomy:

> > Exposure of carotid.

> > Cross-clamping above and below
the area of stenosis
(heparin given immediately prior to this).

> > Vertical incision.

> > Cerebral blood flow reduced whilst
cross-clamp on, dependent on the
collateral flow via Circle of Willis.

Ipsilateral blood flow can be improved
with a shunt from below to above cross-clamps.

Some surgeons use
shunts routinely,

some only in anaesthetised patients
(as neurological
status cannot be monitored),

some only if perfusion appears inadequate.

> > Atheroma removed,
defect closed by primary closure or using a patch
(synthetic or autologous vein graft).

Using a patch reduces the risk of re-stenosis.

Question 7

disadvantages (4 marks) of performing the CEA under regional anaesthesia?

Answer 7

Disadvantages

Risks associated with blocks; intravascular/
epidural/subarachnoid injection, local
anaesthetic toxicity, phrenic nerve damage
etc.

Risk of need to convert to GA with restricted
airway access intraoperatively.

Needs cooperative patient; surgery may be
prolonged, claustrophobia from drapes,
overheating, full bladder.

Potential for patient movement causing
surgical difficulty.

Potential for patient stress/pain causing
myocardial ischaemia.